<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <meta name="theme-color" content="#000000" />
    <meta name="description" content="Web site created using create-react-app" />
    <title>React App</title>
</head>
<style>
    .a {
        width: 300px;
        height: 300px;
        background-color: pink;
    }

    .b {
        width: 100px;
        height: 100px;
        background-color: blue;
    }
</style>

<body>
    <div class="a" onclick="console.log(1)">
        <div class="b" onclick="console.log(2)">
            <button class="c" onclick="console.log(3)">
                点位
            </button>
        </div>
    </div>
</body>
<script>
    window.addEventListener('click', function (e) {
        console.log(e.target) // button
    })
    // 3 2 1  
</script>

</html>